Former first lady Michelle Obama took to Twitter to stand up for 16-year-old climate activist Greta Thunberg, who was the subject of one of President Trump’s tweet storms Thursday morning. “Don’t let anyone dim your light,” Obama wrote in a tweet to Thunberg. “Like the girls I’ve met in Vietnam and all over the world, you have so much to offer us all. Ignore the doubters and know that millions of people are cheering you on.” Trump, 73, took aim at Thunberg after she was named Time’s Person of the Year, calling the honor “so ridiculous.” “Greta must work on her Anger Management problem, then go to a good old fashioned movie with a friend! Chill Greta, Chill!” Trump said in a tweet. First lady Melania Trump, who has spearheaded the #BeBest anti-bullying campaign during her time in the White House, has not commented on her husband’s tweets.